There is a need to provide both convenience and comfort for engineers who must wear a safety cap under a very hot sun so that the engineers can enjoy cool ventilation air at those times. In addition, a practical solution is needed to provide such a safety cap for engineers. Preferably, such a safety cap should contain a fan that can be fitted inside the top of the cap and is driven by a motor. In addition, it would be useful if the fan inside the cap can also be used as an ordinary fan, such as when the engineer is resting under a shelter such as a tree.